Geothermal pavement systems are a novel type of energy geostructure. They use sub-surface structures to exchange heat with the ground and, thereby, provide thermal energy in addition to structural support. The thermo-activation of pavements has been largely overlooked in the literature. This research focuses on the development of a detailed three-dimensional (3D) finite-element (FE) model to explore the thermal performance of geothermal pavement systems. The 3D FE model developed was successfully validated with both data measured from a full-scale experiment undertaken in Adelaide, South Australia and other published data. The validated model is further employed to evaluate the long-term performance of a geothermal pavement system under both a traditional system configuration and a hybrid system. Furthermore, a life-cycle cost analysis is performed to explore the cost implication of such pavement systems. Results show that a geothermal pavement with total pipe length of 640 m, or a hybrid system (a geothermal pavement system with a pipe length of 320 m and an auxiliary system) can provide for sufficient space heating and cooling for a typical residential building in Australia. It is found that, compared with conventional heating and cooling systems, the geothermal pavement system is indeed a cost-effective solution. This research study indicates that this pavement technology can be successfully implemented in the field and accurately modelled using FE techniques.